This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. This phase II SBIR application will continue the development of an inexpensive point-of-care card/reader system for monitoring CD4+ cells in HIV-infected subjects, for use in resource poor areas. The technology uses a thin-film laminated microfluidic cassette to collect, count and store the blood sample while the required detecting reagents are stored and injected into the cassettes from the bench top unit. The aims are designed to systematically develop and troubleshoot the device, ultimately validating its readings comparing with standard flow cytometry using whole blood from human subjects to enumerate CD4+ cells in small volumes for less than $1.50 per test.